1. Field of the Invention
The present invention relates to techniques improving the performance of systems that serve content in response to requests from clients. In particular, the present invention relates to an aggregation system and a method for aggregating data received from one or more services, such as data used to dynamically generate web pages or other types of content objects.
2. Description of the Related Technology
In the course of dynamically generating a web page, a web server machine commonly makes service requests over a network to one or more services to obtain the data needed to generate the page. The particular service requests are commonly specified, at least partially, by a document template that is interpreted and/or executed by the web server machine. The template also typically specifies how the retrieved service data is to be assembled into a web page.
The particular service requests used to generate a web page are often “chained,” meaning that one or more service requests cannot be made until the results of one or more other service requests are received. For example, a service request may use the result of another service request as a parameter. Such chaining of service requests often increases page-generation latency by reducing the degree to which data can be retrieved and processed in parallel.
Additional latency is commonly introduced due to the complexity of handling the dependencies and relationships between different service requests. For example, in many cases, an unnecessary delay will occur between the arrival of a particular service request result and the transmission of a service request that is dependent upon that result. As another example, delay is sometimes introduced by unnecessarily making duplicate or redundant service requests.
In many cases, the performance of a distributed web page generation system can be improved by caching the results of service requests on the web server machine. However, the web server machines may not have adequate memory to cache all, or even a significant portion of, the service data likely to be re-used. Moreover, caching schemes do not provide an effective way of handling dependencies among services requests.